The Firefly Alpha is a specialized design to launch light satellites at low cost into low Earth and Sun-synchronous orbits for broadband communication and Earth observation missions. Designed to carry payloads of up to 400 kg (880 lb), the Alpha features carbon composite construction and uses the same basic design for both of its two stages to keep down costs and simplify assembly.
The launcher uses methane and liquid oxygen as propellants, which Firefly says is a first for orbital launchers, though methane has been proposed for landers. Methane was chosen because it's cheap, plentiful, clean-burning and, unlike more conventional fuels, self-pressurizing, so it doesn't require a second pressurization system.A case in point is the small satellite launch company Firefly Space Systems, which recently unveiled its planned Alpha launcher. Aimed at the small satellite launch market, it's designed to launch satellites into low-Earth orbit (LEO) at very low cost with an unconventional aerospike engine. It is also the first orbital launcher to use methane as fuel.